A pharmaceutical composition comprising 1-(2-methoxyethyl)-2-ethyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H -naphtho[2,3-d]imidazol-3-ium bromide as an active ingredient, for use in the treatment of cancer in a combined therapy which comprises the use of one or more anticancer agents selected from the group consisting of carboplatin, cisplatin, paclitaxel, vinorelbine, gemcitabine, irinotecan, docetaxel, doxorubicin and dacarbazine.